Clinical practice requires an improved description of the heart from surface electrocardiographic information; fundamental understanding demands a better accounting of the surface phenomena from the heart's form and behavior. This proposal is to examine extensively the variation in surface potential distribution and the use of the moving equivalent dipole and dipolar pair as the means of transfer of information back and forth between heart and surface. To attain this objective we will sustain an accelerated program for systematic collection of human body surface potential maps. Special attention will be given to the geometry of the heart and thorax to assure reduction of map data to moving dipole format. We will exploit a new rapid method for determining dipole surface effect and obtaining the extradipolar residual. Dipolar component and the residual will be extracted, displayed and examined both for their contribution to the dipolar pair and for the pathophysiologic correlates in the heart. Realistic correction of the theoretical values governing information transfer between heart and surface will be obtained by experimental implantation of artificial generators and by experimental myocardial infarction. BIBLIOGRAPHIC REFERENCES: Johnson, J.C., Flowers, N.C.: History of electrocardiography and vectorcardiography. In Nelson, C. V.: The Theoretical Basis of Electrocardiology. The Clarendon Press, 1976 pp 381-396. Srivastava, T. N., Hussain, M., Gray, L.A., Jr., and Flowers, N. C.: Echocardiographic diagnosis of a struck Bjork-Shiley aortic valve prosthesis. Chest 70:94-98, 1976.